1793 - having served an apprenticeship as a millwright in Bridgwater, he moved to London. 1800 - used his savings to open a workshop in Greenwich, specializing in milling machinery. 1817 - William Cubitt ordered his first prison treadmill from Penn. 1822 - the pioneer iron steamer Aaron Manby was assembled at Deptford an event witnessed by Penn and his son. 1825 - Penn built his first marine engine, improving on the Aaron Manby design. 1832 - stood as a parliamentary candidate at Greenwich. 1838 - was supplying engines to several prominent Thames shipbuilders, notably Ditchburn and Mare.